Trains Q20

20.A train 108 m long moving at a speed of 50 km/hr crosses a train 112 m long coming from opposite direction in 6 seconds. The speed of the second train is:

     A.   48 km/hr

     B.   54 km/hr

     C.   66 km/hr

     D.   82 km/hr

Option : D 

Let the speed of the second train be x km/hr.

Relative speed = (x + 50) km/hr

=		(x + 50) x	5		m/sec
			18

=		250 + 5x		m/sec
		18

Distance covered = (108 + 112) = 220 m.

∴		220		= 6
		250 + 5x 18

⇒ 250 + 5x = 660

⇒ x = 82 km/hr.